Moo Posted October 24, 2009 Share Posted October 24, 2009 I have an SR125 which has been a poor runner for a few years but recently has become unbearable. It either starts first time or not at all on the electric start, it usually just turns over and almost sounds like its trying to backfire. It can be started much more easily by bump starting which often works straight away. Once running it cant make up its mind how to run, it will go for a couple of miles running fine and I can cruise up to 60mph then it will loose all power for a few miles and I cant get above 25mph on level ground, if its being really awkward it will be even more intermittent and I will bunny hop down the street. I’ve cleaned the carburettor and checked the float height, replaced the plug lead, plug cap and spark plug, checked the resistance of the coil all of which seams fine. Cleaned and WD40’d as best I could electrical connections easily accessible with the seat and tank off and noted they were corroded. When ever I remove the spark plug it’s in good condition and when I compare it to the images of spark plugs it indicates the engine is in good condition and running fine, if only someone would let the engine know. If it was my old two stroke bike Id be checking the timing but the SR has a ubiquitous black box which whose operation is a mystery, is it possible the timing isn’t advancing or is there anything that can be adjusted or drift out of calibration? Any help would be welcomed Moo Link to comment Share on other sites More sharing options...
Moderator drewpy Posted October 25, 2009 Moderator Share Posted October 25, 2009 moo do you have a fuel filter on the bike? did you check the pet cock and clean? how old is the battery, with electronic ignition you NEED good amps and volts anything under 12.5 is asking for trouble. check charging with multimeter and it should read 13 - 14 volts @ 3k rpm. a duff battery will give the symtoms you describe! drewps Link to comment Share on other sites More sharing options...
Moo Posted October 26, 2009 Author Share Posted October 26, 2009 Thanks drewpy, I will clean the petcock and check for any obstructions, as for the battery its reasonably new but I remember when I replaced it about a year ago it wasn’t the recommended battery but it was the closest match they had in stock, I had to cut away some of the plastic holder to make it fit. I will check the rating of the battery to make sure its up to scratch and check the voltage / charging. Moo Link to comment Share on other sites More sharing options...
jkkl Posted April 30, 2010 Share Posted April 30, 2010 Its the black box under the seat (cdi unit). I had the same problem with myne and i changed that box and then it was fine Link to comment Share on other sites More sharing options...
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